1. Field of the Invention
The present invention relates to a partition device for use in a heat exchanger, and more particularly to a heat exchanger tank partition device which changes the flow path of the heat exchange medium passing through the heat exchanger.
2. Description of the Prior Art
Heat exchange devices used in conventional air-conditioning equipment and the like include heater cores of heater units and cooler unit evaporators and condensers. One such heat exchanger is the parallel flow type which is equipped with a multiplicity of tubes, through which a prescribed heat exchange medium flows, and a header which links these tubes and through which the heat exchange medium flows into and out of the tubes.
In order to increase the heat exchange efficiency, the flow path of the heat exchange medium is changed by partitioning the tank into a plurality of separate chambers. This arrangement can also be used to improve internal thermal conductivity by extending the overall length of the flow path and raising the flow velocity of the heat exchange medium in the tubes.
In the case of a cooler unit, for example, if the amount of coolant in the condenser is always the same the condenser structure could be designed in accordance with the said amount of coolant. In practice, however, there is always some differences in the quantity of coolant used owing to differences in service conditions from unit to unit. When the quantity of coolant is smaller, the nature of the coolant being what it is, it flows along the path of least resistance, producing an uneven flow which impedes the transition of the liquid coolant to the vapor phase, resulting in poor heat exchange efficiency. The cooling medium has three phase states, vapor phase, dual-phase vapor-liquid state, and liquid phase, with the dual-phase vapor-liquid state providing the best heat exchange efficiency. With respect to air-conditioned air having a thermal load, higher heat exchange efficiencies are achieved even with a smaller quantity of coolant by cycling the coolant through the system a number of times, as in the case of two or three pass systems. However, too many passes will produce resistance when there is a larger quantity of coolant, and overcooling when there is a smaller quantity of coolant. With respect to the design of condensers and other heat exchangers, it therefore becomes a matter of selecting the optimum number of passes. Achieving the requisite number of passes is ensured by partitioning heat exchanger tanks into the requisite number of chambers.
Disclosures of arrangements for providing such partitioning include that of Japanese Laid-open Patent Application No. 63-49193/1988. The principal parts of a such a conventional heat exchanger tank partition arrangement using a two-pass parallel-flow condenser will now be described, with reference to FIGS. 12 to 14.
With reference to FIG. 12, which shows a cross-sectional plan view of the condenser 1, coolant (heat exchange medium) from a compressor (not shown) is introduced into a first tank portion 2, passes through a multiplicity of outward tubes 3, a second tank portion 4 and a multiplicity of inward tubes 5, and from there into the liquid tank (not shown) of the next stage.
The first tank portion 2 is divided into an outward tank chamber 2A and an inward tank chamber 2B by a round partition plate 6. Fins 7 are disposed between tubes 3 and 5.
FIG. 13 is an enlarged plan view showing a simplified representation of the arrangement for the partitioning of the first tank portion 2, and FIG. 14 is a front view of the round partition plate 6. A partition groove 8 that is as wide as the thickness of the round partition plate 6 is formed at the point at which the first tank portion 2 is partitioned, and formed in the round plate 6 is a cutout portion 9 the depth of which equals the thickness of the first tank portion 2. After the round plate 6 is fitted into the partition groove 8, the round plate 6 is brazed to the first tank portion 2.
However, this arrangement can give rise to problems of reliability. This is owing to the fact that as the round plate 6 is merely fitted into the partition groove 8, any deflection of the round plate 6 that may occur during assembly or transportation, or during positioning in the brazing chamber (not shown), can mar the integrity of the brazing, causing the heat exchange medium to leak and making repairs necessary.
There are also problems relating to manufacturing efficiency. That is, forming the partition requires the steps of forming the partition groove 8 in the tank portion, stamping the cutout portion 9 in the round plate 6 inserting the round plate 6 into the partition groove 8 and attaching the plate 6, and care has to be taken to ensure that there will be no leakage of coolant.